Antibiotic susceptibility, heteroresistance, and updated treatment strategies in Helicobacter pylori infection

Evidence of Helicobacter pylori heterogeneity in human stomachs by susceptibility testing and characterization of mutations in drug-resistant isolates

Heterogeneity of Helicobacter pylori communities contributes to its pathogenicity and diverse clinical outcomes. We conducted drug-susceptibility tests using four antibiotics, clarithromycin (CLR), amoxicillin (AMX), metronidazole and sitafloxacin, to examine H. pylori population diversity. We also analyzed genes associated with resistance to CLR and AMX. We examined multiple isolates from 42 Japanese patients, including 28 patients in whom primary eradication with CLR and AMX had failed, and 14 treatment-naïve patients. We identified some patients with coexistence of drug resistant- and sensitive-isolates (drug-heteroR/S-patients). More than 60% of patients were drug-heteroR/S to all four drugs, indicating extensive heterogeneity. For the four drugs except AMX, the rates of drug-heteroR/S-patients were higher in treatment-naïve patients than in primary eradication-failure patients. In primary eradication-failure patients, isolates multi-resistant to all four drugs existed among other isolates. In primary eradication-failure drug-heteroR/S-patients, CLR- and AMX-resistant isolates were preferentially distributed to the corpus and antrum with different minimum inhibitory concentrations, respectively. We found two mutations in PBP1A, G591K and A480V, and analyzed these in recombinants to directly demonstrate their association with AMX resistance. Assessment of multiple isolates from different stomach regions will improve accurate assessment of H. pylori colonization status in the stomach.

Best Practices for Helicobacter pylori Management

For decades, antimicrobial therapy for Helicobacter pylori infection has been given empirically, and the results of therapy (success or failure) have either not been confirmed or when confirmed have not been used to modify prescribing behavior. These practices coupled with increasing antibiotic resistance have resulted in low cure rates overall. Susceptibility testing for H pylori has increasingly become available, especially in the United States. Availability of susceptibility-based therapy has encouraged adoption of the principles of antimicrobial stewardship for H pylori infection (eg, limiting antibiotic choice to antibiotics for which the infection is susceptible given at optimal doses, formulations, frequency of administration, and duration). Antimicrobial regimens can now be classified as empiric therapies, susceptibility-based therapies, potentially effective therapies requiring optimization, and therapies containing unneeded antibiotics that should not be used. This article describes current best practices and recommendations for integrating culture-based and molecular-based susceptibility testing into H pylori therapy.

Analysis of Helicobacter pylori resistance in patients with different gastric diseases

Helicobacter pylori (H. pylori) resistance is the most important risk factor for eradication failure. However, in most regions, antibiotic resistance rates of H. pylori in patients with different types of gastric mucosal lesions are still unclear. An 8-year clinical retrospective cohort study involving 2847 patients was performed. In this study, we first summarized and compared the resistance status of H. pylori in different years, ages, sexes, and gastric diseases. The resistance profiles of amoxicillin (AMX), clarithromycin (CLR), levofloxacin (LVX) and furazolidone (FR) and their changing trends in the clinic were described. Then, multiple antibiotic resistance in different gastric diseases and years were described and compared. The relationship between proton pump inhibitor (PPI) medication history and antibiotic resistance in H. pylori was also explored. Finally, an antibiotic resistance risk model was constructed for clinical resistance risk prediction. The overall resistance rates of AMX, CLR, LVX and FR in gastric diseases were 8.18%, 38.11%, 43.98%, and 13.73%, respectively. The mono resistance, double resistance, triple resistance, and quadruple resistance rates were 30.17%, 25.96%, 6.46%, and 0.63%, respectively. Compared with the period from 2014 to 2016, the rates of mono-resistance and multiple resistance all showed relatively downward trends in the past 5 years. Factors including age, sex, type of gastric lesions and recent PPI treatment history are associated with the antibiotic resistance rate of H. pylori. Atrophic gastritis is an important clinical feature of high-risk antibiotic resistance in H. pylori-infected patients. Patients with atrophic gastritis have higher risk of resistant strains infection. In this study, our data provide the association between antibiotic resistance of H. pylori and gastritis pattern, which indicate the higher risk of resistant strain infection if the patients with atrophic gastritis, PPI history and older age.

Efficacy of genotypic susceptibility-guided tailored therapy for Helicobacter pylori infection: A systematic review and single arm meta-analysis

BACKGROUND AND AIM

The prevalence of antibiotic resistance for Helicobacter pylori (H. pylori) has been increasing over the year, making it more difficult for traditional empirical therapy to successfully eradicate H. pylori. Thus, tailored therapy (TT) guided by molecular-based antibiotic susceptibility testing (AST) has been frequently recommended. We conducted a single-arm meta-analysis to determine the efficacy of tailored therapy guided by molecular-based AST.

METHODS

A systematic literature review was performed on multiple databases, and studies on molecular-based TT were included. The eradication rates of TT by intention-to-treat (ITT) and per-protocol (PP) analyses were pooled respectively.

RESULTS

A total of 35 studies from 31 literature (4626 patients) were included in the single-arm meta-analysis. Overall, the pooled eradication rate of TT was 86.9% (95% CI:84.7%-89.1%) by the ITT analysis, and 91.5% (95% CI:89.8%-93.2%) by PP analysis. The pooled eradication rates of first-line TT and rescue TT were 86.6% and 85.1% by ITT analysis and 92.0% and 87.9% by PP analysis, respectively. When tailored rescue therapy was based on the genotypic resistance to at least four antibiotics, the pooled eradication rates reached 89.4% by ITT analysis and 92.1% by PP analysis. For genotype-susceptive strains, the pooled eradication rate of TT with targeted antibiotics was 93.1% (95% CI:91.3%-94.9%), among which the pooled eradication rate of tailored bismuth quadruple therapy was the highest (94.3%). Besides, the eradication rate of 7-day TT or tailored triple therapy without bismuth for genotype-susceptive strains could both reach more than 93.0%.

CONCLUSION

Tailored therapy guided by molecular-based AST can achieve somewhat ideal therapeutic outcomes. TT with a 7-day duration or without bismuth for genotype-susceptible strains can achieve good eradication efficacy. The effectiveness of TT can be improved to some extent by expanding the coverage of AST or by adding bismuth.

Relationship between antibiotic resistance and the cagA and vacA genotypes among Helicobacter pylori strain isolates from patients in Xi'an

The issue of drug resistance of Helicobacter pylori is becoming increasingly serious. To analyze the correlation between the cagA and vacA genotypes of H. pylori strains and their resistance to metronidazole, levofloxacin, and clarithromycin in patients in Xi'an, we studied 117 H. pylori strains isolated from patients in Xi'an. Antibiotic susceptibility testing of H. pylori was performed. The cagA and vacA genotypes were investigated using PCR. Among 117 strains of H. pylori, the rate of detection of cagA was 91.45% (107/117), among which the detection rate of East Asian-type cagA was 85.05% (91/107) and that of Western-type cagA was 14.95% (16/107). There were only two genotypes of vacA: s1m1 and s1m2. The detection rate of vacAs1m1 was 47.01% (55/117) and that of vacAs1m2 was 52.99% (62/117). The dominant strains in Xi'an were cagA + vacAs1m2 strains. The metronidazole resistance rate of vacAs1m2 H. pylori strains was significantly higher than that of vacAs1m1 H. pylori strains (91.94% vs. 69.09%, P = 0.002). The levofloxacin resistance rate of Western-type cagA strains was significantly higher than that of East Asian-type cagA strains (56.25% vs. 20.88%, P = 0.004). The metronidazole resistance rate of cagA + vacAs1m2 H. pylori strains was significantly higher than that of cagA + vacAs1m1 H. pylori strains (91.23% vs. 66.00%, P = 0.001). Our results showed that Western-type cagA strains were more likely to develop levofloxacin resistance than East Asian-type cagA strains. VacAs1m2 strains were more prone to metronidazole resistance than vacAs1m1 strains.

Current paradigms in the management of refractory Helicobacter pylori infection

Helicobacter pylori is the most prevalent chronic bacterial infection, with approximately half of the world's population estimated to be colonized. The World Health Organization (WHO) has classified Helicobacter pylori as a class-I carcinogen. All main society guidelines recommend its eradication in infected individuals. The global trend indicates that eradication rates are decreasing annually and the likelihood of eradication decreases with each unsuccessful therapeutic attempt. Resistance to antibiotics in H. pylori strains is the leading cause for eradication failure. Still, drug resistance and treatment failure may be complex, multi-dimensional and associated with several other factors. Knowledge of these factors can aid in optimizing eradication rates. This review will focus on the factors associated with refractory H. pylori, with a particular emphasis on antibiotic resistance mechanisms and their clinical implications. Also, the most recent literature and recommendations available for determining an appropriate regimen after the failure of the first attempt at eradication will be discussed.

Antibiotic resistance, heteroresistance, and eradication success of Helicobacter pylori infection in children

BACKGROUND

Antibiotic resistance is a well-known factor of Helicobacter pylori eradication failure. Heteroresistance indicates the coexistence of resistant and susceptible strains and might lead to underestimating antimicrobial resistance. This study aims to evaluate the susceptibility profile, the frequency of heteroresistance of H. pylori strains, and their effect on eradication success in a pediatric population.

MATERIALS AND METHODS

Children aged 2-17 years who underwent an upper gastrointestinal endoscopy from 2011 to 2019 with positive H. pylori status were included. Susceptibility was measured by disk diffusion and E-test. The difference in susceptibility profiles between isolates from the antrum and the corpus was used to detect heteroresistance. For those who received eradication treatment, we evaluated eradication rate and factors affecting treatment success.

RESULTS

Inclusion criteria were met by 565 children. Strains susceptible to all antibiotics were detected in 64.2%. Primary resistance rates for clarithromycin (CLA), metronidazole (MET), levofloxacin (LEV), tetracyclin (TET), and amoxicillin (AMO) were 11%, 22.9%, 6.9%, 0.4%, and 0% and secondary resistance rates were 20.4%, 29.4%, 9.3%, 0%, and 0%. Heteroresistance was present in untreated children in 2%, 7.1%, 0.7%, 0.7%, and 0% for CLA, MET, LEV, TET, and AMO. First-line eradication rates were 78.5% in intention-to-treat (ITT), 88.3% in full-analysis-set (FAS), and 94.1% in per-protocol (PP). Factors affecting eradication success were the duration of treatment when the triple-tailored treatment was used, the number of daily doses of amoxicillin administered, and the patient's adherence to treatment.

CONCLUSIONS

This study shows the presence of relatively low primary resistance rates for H. pylori isolates but demonstrates the presence of heteroresistance in our population. Routine biopsies from the antrum and corpus must be considered for susceptibility testing to allow tailored treatments and increase eradication rates. Treatment success is affected by treatment choice, correct dosing of medications, and adherence. All these factors should be considered when evaluating the efficacy of an eradication regimen.

Drug-Resistant Helicobacter pylori: Diagnosis and Evidence-Based Approach

Helicobacter pylori (H. pylori) is the most common chronic bacterial infection, affecting approximately half of the world's population. H. pylori is a Class I carcinogen according to the World Health Organization, and the International Agency for Research on Cancer (IARC) has linked it to 90% of stomach cancer cases worldwide. The overall pattern points to a yearly reduction in eradication rates of H. pylori with the likelihood of success further decreasing after each unsuccessful therapeutic effort. Antimicrobial resistance in Helicobacter pylori is a major public health concern and is a predominant cause attributed to eradication failure. As a result, determining H. pylori's antibiotic susceptibility prior to the administration of eradication regimens becomes increasingly critical. Detecting H. pylori and its antimicrobial resistance has traditionally been accomplished by time-consuming culture and phenotypic drug susceptibility testing. The resistance of H. pylori to different antibiotics is caused by various molecular mechanisms, and advances in sequencing technology have greatly facilitated the testing of antibiotic susceptibility to H. pylori. This review will summarize H. pylori antibiotic resistance patterns, mechanisms, and clinical implications. We will also review the pros and cons of current antibiotic susceptibility testing methods. Along with a comparison of tailored susceptibility-guided regimens and empirical therapy based on the latest evidence, an evidence-based approach to such situations will be explored.

Antibiotic resistance characteristics and risk factors analysis of Helicobacter pylori strains isolated from patients in Liaoning Province, an area in North China

Background

The prevalence of Helicobacter pylori (H. pylori) keeps rising while the eradication rate continues to decline due to the increasing antibiotic resistance. Regional variations of antimicrobial resistance to H. pylori have been recommended by guidelines in recent years. This study aims to investigate the antibiotic resistance rate of H. pylori and its association with infected subjects' characteristics in Liaoning Province, an area in north China.

Methods

Gastric tissues from 178 H. pylori positive participants without previous antibiotic use within four weeks were collected for H. pylori culture. Antibiotic susceptibility to furazolidone (AOZ), tetracycline (TC), levofloxacin (LFX), metronidazole (MET), clarithromycin (CLA), and amoxicillin (AMX) were examined with the agar dilution method. Associations between H. pylori resistance and patient characteristics were further analysed.

Results

No resistance was observed in AOZ or TC. For LFX, MET, CLA, and AMX, the overall resistance rates were 41.10%, 79.14%, 71.78%, and 22.09% respectively. There were significant differences between resistance to CLA and MALToma (P = 0.021), and between resistance to MET and age (P < 0.001).

Conclusions

The primary resistant rates of LEX, MET, CLA, and AMX were relatively high in Liaoning. Treatment effectiveness improvement could be achieved by prior antimicrobial susceptibility tests before antibiotic prescription.

Factors associated with treatment failure, and possible applications of probiotic bacteria in the arsenal against Helicobacter pylori

INTRODUCTION

Helicobacter pylori is a widespread helical Gram-negative bacterium, which causes a variety of stomach disorders, such as peptic ulcer, chronic atrophic gastritis, and gastric cancer. This microbe frequently colonizes the mucosal layer of the human stomach and survives in the inhospitable microenvironment, by adapting to this hostile milieu.

AREAS COVERED

In this extensive review, we describe conventional antibiotic treatment regimens used against H. pylori including, empirical, tailored, and salvage therapies. Then, we present state-of-the-art information about reasons for treatment failure against H. pylori. Afterward, the latest advances in the use of probiotic bacteria against H. pylori infection are discussed. Finally, we propose a polymeric bio-platform to provide efficient delivery of probiotics for H. pylori infection.

EXPERT OPINION

For effective probiotic delivery systems, it is necessary to avoid the early release of probiotics at the acidic stomach pH, to protect them against enzymes and antimicrobials, and precisely target H. pylori bacteria which have colonized the antrum area of the stomach (basic pH).

Mechanisms and Clinical Relevance of Pseudomonas aeruginosa Heteroresistance

Abstract Background: Pseudomonas aeruginosa is an opportunistic pathogen that can cause various life-threatening infections. Several unique characteristics make it the ability of survivability and adaptable and develop resistance to antimicrobial agents through multiple mechanisms. Heteroresistance, which is a subpopulation-mediated resistance, has received increasing attention in recent years. Heteroresistance may lead to unexpected treatment failure if not diagnosed in time and treated properly. Therefore, heteroresistant Pseudomonas aeruginosa infections pose considerable problems for hospital-acquired infections. However, the clinical prevalence and implications of Pseudomonas aeruginosa heteroresistance have not been reviewed. Results: In this work, the aspects of the clinically reported heteroresistance of Pseudomonas aeruginosa to commonly used antibiotic agents are reviewed. The prevalence, mechanisms, and clinical relevance of each reported heteroresistant Pseudomonas aeruginosa are discussed.

Clinical Implications of Helicobacter pylori Antibiotic Resistance in Italy: A Review of the Literature

Helicobacter pylori (H. pylori) resistance to antibiotics has increased worldwide in recent decades, especially to clarithromycin. As a result, the World Health Organization (WHO) identified clarithromycin-resistant H. pylori as a "high priority" pathogen in 2017. As international guidelines recommend empirical therapy as first-line treatment, it is crucial to know local resistance rates and history of antibiotic use to determine the most appropriate first-line antibiotic treatment. Italy is one of the European countries with the highest prevalence of H. pylori infection and the highest percentage of antibiotic-resistant H. pylori. The aim of this review is to summarize all data on H. pylori antibiotic resistance in Italy in order to quantify the current rate and determine the most effective therapeutic approach. The study confirms an elevated level of resistance to clarithromycin, metronidazole, and levofloxacin in Italy. In addition, our results show a satisfactory eradication rate for a bismuth-based regimen when used as first- or second-line treatment. Naive patients are also successfully treated with clarithromycin-based quadruple therapies. Considering the good results of bismuth-based therapy as recovery therapy, this argues for the potential use of clarithromycin quadruple therapy as a first-line treatment.

The influence of gastric atrophy on Helicobacter pylori antibiotics resistance in therapy-naïve patients

Background

Antibiotic susceptibility of Helicobacter pylori to antibiotics may vary among different niches of the stomach. The progression of chronic H. pylori gastritis to atrophy changes intragastric physiology that may influence selection of resistant strains.

Aim

To study the antibiotic resistance of H. pylori taking the severity of atrophic gastritis in antrum and corpus into account.

Methods

Helicobacter pylori-positive patients (n = 110, m = 32, mean age 52.6 ± 13.9 years) without prior H. pylori eradication undergoing upper gastrointestinal (GI) endoscopy for dyspeptic symptoms were included in a prospective study. Patients were stratified into three groups depending on the grade of atrophy: no atrophy (OLGA Stage 0), mild atrophy (OLGA Stage I–II) and moderate/severe atrophy (OLGA Stage III–IV). Two biopsies each from the antrum and the corpus and one from the angulus were taken and assessed according to the updated Sydney system. H. pylori strains were isolated from antrum and corpus biopsies and tested for antibiotic susceptibility (AST) for amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and rifampicin by the agar dilution methods. A Chi-square test of independence with a 95% confidence interval was used to detect differences in the proportion of patients with susceptible and resistant H. pylori strains.

Results

Among 110 patients, primary clarithromycin resistance (R) was 30.0%, both in the antrum and corpus; metronidazole resistance accounted for 36.4 and 34.5% in the antrum and corpus; and levofloxacin was 19.1 and 22.7% in the antrum and corpus, respectively. Resistance rates to amoxicillin, tetracycline, and rifampicin were below 5%. Dual antibiotic resistance rate was 21.8%, and triple resistance rate was 9.1%. There was a significant difference in the resistance rate distribution in antrum (p < 0.0001) and corpus (p < 0.0001). With increasing severity of atrophy according to OLGA stages, there was a significant increase in clarithromycin-R and metronidazole-R.

Conclusion

In treatment-naïve patients, antibiotic resistance and heteroresistance were related to the severity of atrophy. The high clarithromycin resistance in atrophic gastritis suggests that H. pylori antibiotic susceptibility testing should always be performed in this condition before selecting the eradication regimen.

Prevalence of antibiotic heteroresistance associated with Helicobacter pylori infection: A systematic review and meta-analysis

BACKGROUND

Heteroresistance is a general term to describe diverse responses to specific antibiotics that can occur due to infection with either multiple bacterial strains or microevolution of a single strain during chronic infection. Due to limited information regarding heteroresistance Helicobacter pylori (H. pylori) infection, the current study was carried out to evaluate the prevalence of this phenomenon.

METHODS

For this study, all potential relevant studies were collected by searching international databases such as ISI Web of Science, PubMed, Scopus, ScienceDirect, ProQuest, Embase, DOAJ, China National Knowledge Infrastructure (CNKI), and Google Scholar. Finally, the frequency of heteroresistance H. pylori infection was measured using the event rate corresponding to 95% confidence intervals.

RESULTS

A total of 26 studies met our criteria; the eligible studies were related to the years 2001-2022. Our results showed that the prevalence of heteroresistance H. pylori strains was 60.1% to clarithromycin, 61.1% to metronidazole, 46.1% to levofloxacin, 3.8% to amoxicillin, and 21.1% to tetracycline. Our literature review also showed discrepancy of antimicrobial susceptibility test in strains isolated from different anatomical sites of the stomach. Heteroresistance H. pylori infection in developing countries is mostly due to infection with multiple H. pylori strains, while in developed countries it is due to microevolution of a single H. pylori strain in response to antibiotic pressure.

CONCLUSIONS

Heteroresistance H. pylori infection interferes with successful therapy and eventually can lead to the treatment failure. If a biopsy is taken from only one gastric site, resistant strains of H. pylori may be underestimated. Considering the role of heteroresistance H. pylori infection in treatment failure, it is very important for gastroenterologists to improve their knowledge about this fact. Regardingly, new guidelines should be developed and designed for the management and treatment of heteroresistance H. pylori infection.

Chitosan-curcumin complexation to develop functionalized nanosystems with enhanced antimicrobial activity against hetero-resistant gastric pathogen

With the apparent stagnation in the antibiotic discovery and the propagation of multidrug resistance, Helicobacter pylori associated gastric infections are hard to eradicate. In pursuance of alternative medicines, in this study, covalent modification of chitosan (CS) polymer with curcumin (Cur) was accomplished. Proton Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy elucidated the covalent interaction between Cur and CS with characteristic peak of imine functional group (C=N). Scanning Electron Microscopy provided visual proof for surface topology, while size and zeta potential values further affirmed the development of curcumin functionalized chitosan nanosystems (Cur-FCNS). The complexation efficiency of CS with Cur was found as 70 ± 3% at an optimal ratio of 5:1 for CS and Cur, respectively. Cur-FCNS developed with ionic gelation and ultrasonication method demonstrated synergistic anti-H. pylori activity in growth-kinetics and anti-biofilm assays, which was superior to free Cur and even chitosan nanosystems. Under simulated gastric conditions, Cur-FCNS revealed cumulative-release of only 16 ± 0.8% till 40 h, which indicated its improved stability to interact with H. pylori. In silico findings affirmed high binding affinity of Cur-FCNS with multiple bacterial virulence factors. Thus, our results affirmed the exceptional potential of Cur-FCNS as next-generation alternative-medicine to treat resistant H. pylori.

Multicenter Evaluation of a Gradient Diffusion Method for Antimicrobial Susceptibility Testing of Helicobacter pylori

Helicobacter pylori is an important human pathogen associated with peptic ulcer disease, dyspepsia, and gastric malignancy. Antimicrobial susceptibility testing (AST) is often requested for patients who fail eradication therapy. The Clinical and Laboratory Standards Institute (CLSI) reference method, agar dilution (AD), is not performed in most laboratories and maintaining organism viability during transit to a reference laboratory is difficult. We assessed the performance of the Etest (bioMérieux) as a method for H. pylori AST in comparison to AD. Etest MICs were determined for 83 H. pylori isolates at ARUP and Cleveland Clinic (CC). Categorical agreement (CA), very major, major, and minor errors (VME, ME, and mE) were determined for Etest using AD performed at Mayo Clinic Laboratories as the reference method. Testing on isolates with errors was repeated to determine final results summarized below. For clarithromycin, 66.3% of isolates were resistant (R) by AD; Etest results at each laboratory showed 1mE (1.2%) and 1 ME (3.8%). For tetracycline, only 2 isolates were R by AD; a single VME occurred at both sites (98.8% CA, 50% VME) with the same isolate. Applying EUCAST levofloxacin breakpoints to interpret ciprofloxacin results, 60.2% of isolates were R by AD; ARUP CA was 97.6% (1 ME (3%), 1 VME (2%)) and CC CA was 96.3% (1 ME (3%), 2 VMEs (4%)). Despite high error rates, the categorical agreement was acceptable (>90%) for all three antibiotics between AD and Etest. In-house susceptibility testing by gradient diffusion can allow for testing of fastidious organisms that may not survive transport to specialized laboratories; however, the method is not without technical challenges. Characterization of resistance mechanisms, increased AD dilutions, and testing from the same inoculum may determine if the observed errors reflect technical issues or breakpoints that need optimization.

IMPORTANCE Routine antimicrobial susceptibility testing (AST) of Helicobacter pylori by agar dilution is difficult to perform and not practical in most clinical microbiology laboratories. The Etest gradient diffusion method can be a reliable alternative for H. pylori AST with the advantage of being a less laborious quantitative method. This work reveals that an optimized Etest method can provide acceptable performance for H. pylori AST and describes the challenges associated with this methodology.

Establishment of a TaqMan-MGB probe multiplex real-time PCR system for one-step levofloxacin and clarithromycin resistant Helicobacter pylori detection

Due to the abuse of antibiotics, the prevalence of antibiotic resistant Helicobacter pylori strains continues to increase. Therefore, antibiotic resistance assessment is now essential in addition to general H. pylori diagnosis in medical institutions to fulfill clinicians administering effective antibiotic regimens. However, the conventional antibiotic resistance assessment methods, such as in vitro antibiotic susceptibility test and E-test, are skilled-staff dependent and time-consuming. The aim of this study was to establish an easy-operating TaqMan-MGB probe multiplex real-time PCR system for one-step detection of levofloxacin and clarithromycin resistance mutations with concurrent H. pylori infection diagnosis. Through the optimization of primers, probes and reaction buffers, this proposed system could accurately distinguish the recombinant plasmids with different mutation markers. More importantly, the diagnosis results of this detection system exhibited excellent consistence with the gold standard of gastric biopsy and Sanger sequencing on the detection of H. pylori infection and relevant antibiotic resistant strains, the Kappa values of which all exceeded 0.90. In addition, the results of this detection system could also be applied for the prevalence statistics of antibiotic resistance patterns for patients by age, gender and geographical location. This simple and rapid system should be beneficial for clinicians issuing personalized treatments according to the patient's H. pylori strains and avoid the abuse of antibiotics.

High prevalence of unstable antibiotic heteroresistance in cyanobacteria causes resistance underestimation

Both cyanobacterial bloom and antibiotic resistance have aggravated worldwide and posed a global threat to public health in recent years. Cyanobacteria can exhibit discrepancy between their resistance genotype and susceptible phenotype due to antibiotic heteroresistance, which leads to difficulties in unambiguously classifying cyanobacterial strains as susceptible or resistant. Here we profiled the prevalence and mechanisms of antibiotic heteroresistance in cyanobacterial strains isolated from 50 sites across four eutrophicated lakes in China. Among 300 cyanobacterial isolates tested against 19 different antibiotics, over 90% of cyanobacterial isolates exhibited HR to multiple antibiotics and 19.5% of isolate/antibiotic interactions classified as susceptible by traditional minimum inhibitory concentration (MIC) estimates were designated heteroresistant. Over 97% of these monoclonal HR cases were unstable, with an increased resistance of subpopulations due to amplification of known resistance genes with high fitness cost. Wide-type cyanobacterial isolates of Synechococcus, Synechocystis, Anabaena and Microcystis aeruginosa exposed to sub-MIC level of four antibiotics evolved high-level resistance with little fitness cost, resulting in stable polyclonal HR. Both stable polyclonal HR and unstable monoclonal HR observed in different cyanobacterial strains can be promoted under environmental levels of antibiotic pressure. The highly prevalent and unstable monoclonal HR with the potential for susceptibility misclassification highlighted underestimation of cyanobacteria-derived antibiotic resistance. Cost-effective strategies should be developed to identify heteroresistance in cyanobacteria and to avoid false positive or negative results in traditional susceptibility testing.

Empirical or susceptibility-guided treatment for Helicobacter pylori infection? A comprehensive review

Although susceptibility-guided therapy is frequently recommended for Helicobacter pylori infection, the evidence available to date supporting this strategy is limited. The aim of the present article is to review the advantages and limitations of the susceptibility-guided and the empirical strategies to treat this infection. We performed a bibliographic search to identify studies investigating H. pylori susceptibility-guided therapy. Culture is not the only way to assess antibiotic resistance, as different polymerase chain reaction-based approaches have been developed as alternative methods. For detecting H. pylori antimicrobial resistance, a molecular approach based on a stool sample might enable more convenient, time-saving methods. Unfortunately, the antimicrobial susceptibility cannot be obtained in all cases. Furthermore, antibiotic susceptibility testing in clinical practice yields useful information only for a few antibiotics: clarithromycin, metronidazole, and quinolones. In addition, susceptibility towards clarithromycin and metronidazole in vitro does not necessarily lead to eradication in vivo. In the case of H. pylori therapy failure, we should not re-administer any of the antibiotics against which H. pylori has probably become resistant. Our updated meta-analysis showed that susceptibility-guided treatment is not better than empirical treatment of H. pylori infection in first-line therapy if the most updated quadruple regimens are empirically prescribed, and similar efficacy results were also demonstrated with the two strategies for second-line therapy. Cumulative H. pylori eradication rate with several successive rescue therapies empirically prescribed reaches almost 100%. Finally, the studies that have evaluated the cost-effectiveness of the susceptibility-guided treatment have achieved contradictory results. In summary, we can conclude that the evidence is too limited to support the generalized use of susceptibility-guided therapy for H. pylori treatment in routine clinical practice, either as first-line or as rescue treatment. Nevertheless, it would be recommended that susceptibility tests are performed routinely, even before prescribing first-line treatment, in specialized centers with an interest in H. pylori management.

Phenotype and Molecular Detection of Clarithromycin and Levofloxacin Resistance in Helicobacter pylori Clinical Isolates in Beijing

Introduction

Understanding drug resistance is important in drug selection for Helicobacter pylori (H. pylori) eradication, and drug resistance data are lacking in Beijing.

Purpose

This cross-sectional study aimed to isolate H. pylori from patients with gastroduodenal diseases and to analyze drug resistance to clarithromycin (CLA) and levofloxacin (LEV), which are used frequently in China.

Patients and Methods

One hundred and seventy-six patients with gastroduodenal diseases undergoing gastroduodenoscopy were selected by convenient sampling. Gastric mucosa samples were cultured and sub-cultured using a new medium broth. Active H. pylori strains were confirmed by microscopy observation as Gram-negative curved bacilli with positive test results for urease, oxidase, and catalase, and H. pylori 16S rRNA amplification by polymerase chain reaction (PCR). CLA and LEV resistance was identified by minimum inhibitory concentration (MIC) tests and sequencing of 23S rRNA, gyrA, and gyrB genes.

Results

From the 176 clinical samples, 112 (112/176, 63.6%) were confirmed with H. pylori infection and 65 (65/176, 36.9%) active H. pylori strains were obtained and further confirmed by MIC assay. Overall, the rates of CLA-resistant and LEV-resistant mutations in the 112 samples were 50.9% and 33.0%, respectively. Mutation related to CLA resistance was A2143G in the 23S rRNA gene and mutations associated with LEV resistance were N87K, D91G, and D91Y in the gyrA gene. Of 112 samples, 22 (19.6%) presented dual resistance to CLA and LEV. Resistance of the H. pylori strains to CLA (r=0.846, P<0.001) and LEV (r=0.936, P<0.001) had a strong correlation in phenotypic and genotypic level.

Conclusion

The results indicated that resistance of CLA and LEV is severe among patients with gastroduodenitis. A good consistency could be found as to drug resistance between genotypic or phenotypic assay, suggested extending the detection of H. pylori drug resistance from the MIC method to a genotypic assay.

Evaluation of the Direct Economic Cost per Eradication Treatment Regimen against Helicobacter pylori Infection in Greece: Do National Health Policy-Makers Need to Care?

Helicobacter pylori (Hp) management has undoubtedly resulted in a notable economic burden on healthcare systems globally, including Greece. Its cost has never been estimated so far, especially during the recent 10-year unprecedented financial crisis. Direct medical and procedural costs for one attempt "outpatient" Hp eradication treatment were estimated as the following: (I) first-line regimens: 10 and 14 days standard triple, 10 and 14 days sequential, 10 and 14 days concomitant non-bismuth quadruple, 14 days hybrid, (II) second-line salvage regimens: 10 and 14 days levofloxacin-containing triple regimens. Treatment costs using prototypes and/or generic drugs were calculated. Drug prices were collected and confirmed from two official online medical databases including all medicines approved by the Greek National Organization for Medicines. Regimens based on generics were more affordable than prototypes and those including pantoprazole yielded the lowest prices (mean: 27.84 €). Paradoxically, 10-day concomitant and 14-day hybrid regimens (currently providing good (90-94%) first-line eradication rates in Greece) cost the same (mean: 34.76 €). The expenditures for Hp eradication treatment regimens were estimated thoroughly for the first time in Greece. These data should be taken into account by Public Health policymakers both in Greece and the European Union, aiming for a better and less expensive therapeutic approach.

Helicobacter pylori eradication regimens in an antibiotic high-resistance European area: A cost-effectiveness analysis

INTRODUCTION

Helicobacter pylori infection (H pylori-I) affects more than half of the global population and consists an important burden to public health and healthcare expenditures, by contributing to many diseases' pathogenesis.

AIM

This study aimed to evaluate the current nonbismuth quadruple eradication regimens in a high antibiotic resistance area, such as Greece, concerning their cost-effectiveness, especially during financial crisis period.

MATERIALS AND METHODS

Eight hundred and nine patients who received eradication treatment against H pylori-I were included to evaluate five different regimens, using amoxicillin, clarithromycin, and metronidazole as antibiotics and one proton-pump inhibitor, based on their current eradication rates. Regimes compared 10-day concomitant use of (a) pantoprazole or (b) esomeprazole; 10-day sequential use of (c) pantoprazole or (d) esomeprazole; and 14-day hybrid using esomeprazole. Cost-effectiveness analysis ratio (CEAR) and incremental cost-effectiveness ratios were calculated taking into account all direct costs and cases who needed second-line treatment. Additionally, sensitivity analysis was performed to predict all potential combinations.

RESULTS

Ten-day concomitant regimen with esomeprazole was characterized by the lowest CEAR (179.17€) followed by the same regimen using pantoprazole (183.27€). Hybrid regimen, although equivalent in eradication rates, was found to have higher CEAR (187.42€), whereas sequential regimens were not cost-effective (CEAR: 204.12€ and 216.02€ respectively).

DISCUSSION

This is the first study evaluating the cost-effectiveness of H pylori-I treatment regimens in a high clarithromycin-resistance (≈26.5%) European area, suggesting the 10-day concomitant regimen with generics using esomeprazole 40 mg as the most appropriate one. National and regional guidelines should include cost-effectiveness in their statements, and further studies are required to clarify the necessity of a wide "test and treat" policy for H pylori-I.

Molecular characterization and prevalence of antibiotic resistance in Helicobacter pylori isolates in Kuala Lumpur, Malaysia

Aims and objectives

Helicobacter pylori has been classified as high priority pathogen by the WHO in 2017. The emergence of antibiotic-resistant strains is one of the main causes of treatment failure in H. pylori infection. This study determined and characterized primary and secondary resistances in H. pylori in Malaysia.

Materials and methods

Gastric biopsies from antrum (n=288) and corpus (n=283) were obtained from 288 patients who underwent endoscopy at Universiti Kebangsaan Malaysia Medical Center (UKMMC), Kuala Lumpur, Malaysia. Antibiotic susceptibility to six classes of antibiotics was determined by the E-test. Mutations conferring in resistance in functional genes were identified by PCR and sequencing.

Results

Overall resistance rates to metronidazole, clarithromycin and levofloxacin were 59.3% (35/59), 35.6% (21/59) and 25.4% (15/59), respectively. Secondary isolates showed significantly higher resistance rates to clarithromycin compared to the primary isolates. Mixed infection with susceptible and resistant isolates was observed in 16.2% (6/37) of cases, of which 83.3% (n=5) had infection with the same strain. 41% (18/44) of isolates were resistant to more than one class of antibiotics of which 50% (9/18) were multidrug-resistant, two being primary and seven being secondary isolates. Mutations in rdxA, 23S rRNA and gyrA genes were associated with resistance to metronidazole, clarithromycin and levofloxacin, respectively.

Conclusion

The high level of resistance to metronidazole, clarithromycin and levofloxacin seen in H. pylori isolates in our setting warrants the need for continuous surveillance and highlights caution in use of antibiotics generally used as first-line therapy in H. pylori eradication regimen.

Ceftriaxone use in a tertiary care hospital in Kilimanjaro, Tanzania: A need for a hospital antibiotic stewardship programme

Excessive use of antibiotics, especially watch group antibiotics such as ceftriaxone leads to emergence and spread of antimicrobial resistance (AMR). In low and middle-income countries (LMICs), antibiotics are overused but data on consumption is scarcely available. We aimed at determining the extent and predictors of ceftriaxone use in a tertiary care university teaching hospital in Kilimanjaro, Tanzania. A hospital-based cross-sectional study was conducted from August 2013 through August 2015. Patients admitted in the medical, surgical wards and their respective intensive care units, receiving antimicrobials and other medications for various ailments were enrolled. Socio-demographic and clinical data were recorded in a structured questionnaire from patients' files and logistic regression was performed to determine the predictors for ceftriaxone use. Out of the 630 patients included in this study, 322 (51.1%) patients were on ceftriaxone during their time of hospitalization. Twenty-two patients out of 320 (6.9%) had been on ceftriaxone treatment without evidence of infection. Ceftriaxone use for surgical prophylaxis was 44 (40.7%), of which 32 (72.7%) and 9 (20.5%) received ceftriaxone prophylaxis before and after surgery, respectively. Three (6.8%) received ceftriaxone prophylaxis during surgery. Predicting factors for that the health facility administered ceftriaxone were identified as history of any medication use before referral to hospital [OR = 3.4, 95% CI (1.0-11.4), p = 0.047], bacterial infection [OR = 18.0, 95% CI (1.4-225.7, p = 0.025)], surgical ward [OR = 2.9, 95% CI (0.9-9.4), p = 0.078] and medical wards [OR = 5.0, 95% CI (0.9-28.3), p = 0.070]. Overall, a high ceftriaxone use at KCMC hospital was observed. Antimicrobial stewardship programs are highly needed to monitor and regulate hospital antimicrobial consumption, which in turn could help in halting the rising crisis of antimicrobial resistance.

Novel high resolution melt curve assay for the analysis of predominance of Helicobacter pylori clarithromycin resistance

Clarithromycin resistance is the most common cause of Helicobacter pylori treatment failure and it is attributed to three point mutations, A2142G, A2142C and A2143G, within the 23S rRNA gene. We aimed to determine the prevalence of H. pylori clarithromycin resistance using a novel high resolution melt assay. A total of 151 stool samples were collected from treatment-naïve patients with general gastric discomfort who also performed 13CO2 breath tests. Stool antigen tests were also performed on 126 of the 151 stool samples collected. Bacterial DNA was extracted from the stool and analyzed by comparing it with four reference plasmids incorporating the three mutations and the wild type (WT) sequences. The melt assay detected 106 H. pylori positive samples, of which 54 had a WT sequence, and 52 had a point mutation associated with clarithromycin resistance, including A2142G in 10, A2142C in 13, A2143G in 18 and heterozygosity (multiple peaks) in 11. Compared with the gold standards (13CO2 breath and stool antigen tests), the melt assay had a sensitivity of 100% and 99% and a specificity of 82% and 78%, respectively. Therefore, our stool-based molecular assay is able to identify H. pylori infection and clarithromycin resistance. It could be used for screening prior to administration of clarithromycin eradication therapy.

Panning using a phage-displayed random peptide library to identify peptides that antagonize the Helicobacter pylori ArsS acid-sensing domain

Helicobacter pylori is an important etiological factor involved in chronic gastritis, peptic ulcer, and gastric cancer. There are currently no optimal preventive or therapeutic interventions for H. pylori infection. H. pylori survives in the stomach by sensing and adapting to the highly acidic environment by using the two-component signal transduction system that contains the most widely known gastric acid receptor, ArsRS (which is composed of ArsS and ArsR). This study aimed to identify peptides that antagonize the acid-sensing domain of H. pylori ArsS. These peptides could be used to block the acid-sensing signal and thereby hinder H. pylori adaption to acidic environments to prevent its survival. Using proSite, the functional domains (including the N-terminal acid-sensing domain) of H. pylori J99 ArsS were predicted. The purified recombinant ArsS N-terminal acid-sensing protein (P-ArsS-A) was used as the target in a panning protocol in which peptides from the Ph.D.-7 Phage Display Peptide Library that could bind to P-ArsS-A were identified. As a result, eight phage clones that could specifically bind to P-ArsS-A were obtained and five amino acid sequences were identified, including P03 (MMSYPKH) and P06 (LTPMPNW). An in vitro minimum inhibitory concentration (MIC) evaluation showed that P03 and P06 significantly inhibited the growth of H. pylori J99. The MIC of P03 was 8 μM, and the MIC of P06 was >16 μM, indicating that P03 is a stronger inhibitor compared to P06. This was confirmed by colony counting on blood agar plates after P03 and P06 administration. Using homology modeling and molecular docking analysis, it was shown that P03 and P06 could bind to the ArsS N-terminal domain, and there were four shared binding sites: TYR25, ASN39, ARG73, and GLU74. Additionally, one hydrogen bond was found between P03 and ArsS, which is more cohesive than other forms of bonding (van der Waals force, other non-covalent bonds).

Molecular diagnosis of Helicobacter pylori infection in gastric biopsies: Evaluation of the Amplidiag® H. pylori + ClariR assay

BACKGROUND

Adapted treatments for Helicobacter pylori infection, guided by determining antimicrobial resistance, are associated with high eradication rates. We evaluated the performance of the Amplidiag^® H. pylori + ClariR PCR assay (Amplidiag^® ) for detecting H. pylori and its clarithromycin resistance from gastric biopsies taken during endoscopy in comparison to culture and our "in-house" PCR.

MATERIALS AND METHODS

A total of 127 gastric biopsies were analyzed (98 adults; 29 children). Culture, PCR Amplidiag^® , and in-house PCR were performed in parallel. The in-house PCR combined amplification and sequencing of a 267-bp fragment of the H. pylori 23S rRNA gene. Discrepancies were controlled by amplification of glmM gene.

RESULTS

For detection of H. pylori, Amplidiag^® and the in-house PCR were concordant in 118 of 127 of cases: 66 negative and 52 positive. Discrepancies were observed in nine cases, all with low bacterial load: Amplidiag^® did not detect seven biopsies positive on in-house PCR but detected two positive biopsies that were negative on in-house PCR. Among the 19 of 52 (36%) H. pylori cases resistant to clarithromycin, only four biopsies with mixed populations exhibited discordant results between the two PCR methods. The A2142T mutation was not detected by Amplidiag^® . With the in-house PCR and amplified glmM gene as the reference method, the sensitivity and specificity of Amplidiag^® was 88.5% (95% confidence interval 83-94.1) and 100%.

CONCLUSION

This study demonstrated the high sensitivity of the PCR-based Amplidiag^® H. pylori test, especially with low H. pylori load, and the probability of its clarithromycin resistance analysis. For clinical use, a well-designed trial with a large scale of samples may still be needed.

Antimicrobial resistance among Helicobacter pylori isolates in Alaska, 2000-2016

OBJECTIVES

Alaska Natives experience a high burden of Helicobacter pylori infection and concomitant high rates of gastric cancer. Additionally, the prevalence of antimicrobial-resistant H. pylori has been shown to be high in Alaska. In this study, antimicrobial resistance over time among sentinel surveillance isolates was evaluated and risk factors for carrying antimicrobial-resistant H. pylori were assessed.

METHODS

Through Alaska's H. pylori sentinel surveillance system, antral and fundal biopsies from Alaska Native patients undergoing esophagogastroduodenoscopy for clinical indications during 2000-2016 were collected and cultured. For positive cultures, minimum inhibitory concentrations (MICs) of metronidazole, amoxicillin, clarithromycin, tetracycline and levofloxacin were determined.

RESULTS

A total of 800 H. pylori isolates obtained from 763 patients were tested. Resistance to metronidazole was most common (342/800; 42.8%), followed clarithromycin (238/800; 29.8%), both clarithromycin and metronidazole (128/800; 16.0%) and levofloxacin (113/800; 14.1%). Low proportions of isolates were resistant to amoxicillin and tetracycline. Levofloxacin resistance increased between 2000 and 2016 (P<0.001), but resistance to other antimicrobials did not change over time. Metronidazole and clarithromycin resistance were more common among women (P<0.001 for both), whilst levofloxacin resistance was more common among those with an urban residence (P=0.003). Metronidazole and levofloxacin resistance were more common among older patients (P<0.05).

CONCLUSION

Between 2000 and 2016, a large percentage of H. pylori isolates received by the Alaska Sentinel Surveillance System demonstrated resistance to common antimicrobials. The surveillance system provides valuable information for clinicians to make informed treatment choices for patient with H. pylori.

Enzymatic Transition States and Drug Design

Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.

The Resistance Rate of Helicobacter Pylori to Clarithromycin and Main Mutations on Bacterial Genomic Responsible for Bacterial Resistance: A Comparative Study in Children and Adults, Tehran and Iran

BACKGROUND

High resistance to common antibiotics has become a huge global dilemma in eradicating Helicobacter Pylori infection in both children and adults. The great concern is about the resistance to different classes of antibiotics especially Clarithromycin because of its widespread use.

OBJECTIVES

The present survey aimed to assess the resistance rate to Clarithromycin in Helicobacter Pylori isolated in patients aged less than 15 years as compared to patients older than 15 years of age.

METHODS

In this cross-sectional study, total 72 patients with upper gastrointestinal symptoms requiring diagnostic endoscopy referred to Rasoul-e-Akram Hospital in Tehran during one year (August 2015 to August 2016). Helicobacter Pylori infection was diagnosed in patients using the Rapid Urease Test. The antibiotics resistance was detected in genomes using the real-time polymerase chain reaction (PCR) on 23S rRNA gene.

RESULTS

In total 72 patients, 36 cases aged less than or equal to 15 years and 36 patients were older than 15 years. Of all patients in this study, 17 cases were detected with gene mutations or polymorphisms related to resistance to Clarithromycin. Overall prevalence rate of resistance was reported 23.61%. Three polymorphisms on 23S rRNA gene including A2142G, A2142C, and A2143G were revealed in 47.1%, 5.9%, and 47.1% of patients, respectively. The bacterial resistance to Clarithromycin was observed more prevalent in patients that aged older than 15 years compared to patients younger than 15 years of age. Also, frequent consumption of any type of antibiotics was significantly associated with the higher resistance of bacterium to Clarithromycin.

CONCLUSION

The results of our study regarding the resistance of Helicobacter Pylori to Clarithromycin were similar to findings of other studies around the world. But, the Clarithromycin resistance rate was reported higher in patients older than 15 years of age and those patients who repeatedly received different types of antibiotics regardless of their age. Of all mutations in bacterial genome, the prominent mutations responsible for bacterial resistance to Clarithromycin included A2142C, A2142G, and A2143G nucleotide polymorphism on 23S rRNA gene.

Helicobacter pylori drug resistance: therapy changes and challenges

Helicobacter pylori is a Gram-negative bacterium that causes chronic gastritis, dyspepsia, peptic ulcers, and gastric cancer. Over half the world's population is infected with H. pylori, with higher prevalence in developing countries. Areas covered: In this review, current guidelines on H. pylori therapy, such as the Toronto consensus statement, the Maastricht V/Florence consensus report, and the American College of Gastroenterology guidelines, are compared. Also, we analyzed reports of antimicrobial resistance of H. pylori published in PubMed in the last years to determine current antimicrobial resistance worldwide. Expert commentary: Although H. pylori antimicrobial resistance varies by geographic area, its prevalence has been increasing over time, causing therapy failures and low eradication rates. To best optimize the management of H. pylori infection, H. pylori therapy should be based on patterns of local and individual antimicrobial resistance, if possible.

Potent Potassium-competitive Acid Blockers: A New Era for the Treatment of Acid-related Diseases

Conventional proton pump inhibitors (PPIs) are used as a first-line therapy to treat acid-related diseases worldwide. However, they have a number of limitations including slow onset of action, influence by cytochrome P450 polymorphisms, unsatisfactory effects at night, and instability in acidic conditions. Alternative formulations of conventional PPIs have been developed to overcome these problems; however, these drugs have only introduced small advantages for controlling acid secretion compared to conventional PPIs. Potassium-competitive acid blockers (P-CABs) were developed and have beneficial effects including rapid, long-lasting, and reversible inhibition of the gastric hydrogen potassium ATPase, the proton pump of the stomach. Vonoprazan was recently innovated as a novel, orally active P-CAB. It is currently indicated for the treatment of gastric and duodenal ulcers, reflux esophagitis, and prevention of low-dose aspirin- or nonsteroidal anti-inflammatory drug-related gastric and duodenal ulcer recurrence in Japan. Vonoprazan does not require enteric coating as it is acid-stable, and it can be taken without food because it is quickly absorbed. Vonoprazan accumulates in parietal cells under both acidic and neutral conditions. It does not require an acidic environment for activation, has long-term stability at the site of action, and has satisfactory safety and tolerability. Thus, vonoprazan may address the unmet medical need for the treatment of acid-related diseases.

Antibiotic resistance pattern of Helicobacter pylori strains isolated in Italy during 2010-2016

PURPOSE

Bacterial resistance toward the most used antibiotics is increasing in Helicobacter pylori strains worldwide. Emergence of multidrug resistance significantly affects the efficacy of standard therapy regimens. Therefore, monitoring for primary antimicrobial resistance is essential for H. pylori management in clinical practice.

METHODOLOGY

H. pylori isolates obtained from patients consecutively observed in a single center were tested for primary resistance by using E-test method. Bacterial strains showing MIC values >0.5, >8 and >1 mg/L toward clarithromycin, metronidazole and levofloxacin, respectively, were considered resistant. The trend of antibiotic prevalence, either single or combined, during 2010-2016 was assessed.

RESULTS

Antibiotic susceptibility data were available in 1424 (82.3%) out of 1730 tested patients. The overall resistance for all the three antibiotics showed an increasing trend from 2010 to 2013 (clarithromycin: from 19% to 35.6%; metronidazole: from 33.6% to 45.3%; levofloxacin: from 19% to 29.7%; p < .001), when a plateau until 2016 was observed (clarithromycin: 35.9%; metronidazole: 40.2%; levofloxacin: 29.3%). A similar trend occurred for clarithromycin-metronidazole combined resistance rate (2010: 11.4%; 2013: 28.2%; 2016: 21.9%).

CONCLUSION

Our data suggest that prevalence of primary resistance in H. pylori isolates toward the most frequently used antibiotics probably reached a plateau in the last years.

Benign and malignant gastroduodenal diseases associated with Helicobacter pylori: a narrative review and personal remarks in 2018

The subject of Helicobacter pylori continues to elicit worldwide interest in many research fields. Epidemiological data suggest that the prevalence of the infection is decreasing in Western/developed countries and even in some developing regions, but this is masked by the high prevalence in the most populous regions. Chronic gastritis, caused invariably by the bacterium, was again classified in Kyoto and Helicobacter pylori-associated gastritis was included as a distinct entity. The prevalence of peptic ulcers is decreasing, but bleeding ulcers are a challenging problem, with stable mortality levels even in the endoscopic era. With the extended use of endoscopy, gastric polyps (GP) have become more prevalent: some are associated with the infection, some are not. Autoimmune and Helicobacter-induced gastritis can share common pathogenetic mechanisms. Gastric cancer (GC) is ranked highly on mortality lists worldwide. Its surgical treatment has registered some progress though. Little, if any improvement has been achieved in the medical treatment of advanced GC. With proper organization, GC seems a preventable disease. In spite of many guidelines, the Pan-European registry of Helicobacter pylori management shows that eradication rates obtained in many places are suboptimal. A new therapeutic regimen was compiled with promising pilot results. The results obtained with vonaprazan are limited to Asia. New avenues of both antibiotic and non-antibiotic treatments are expected to accelerate the eradication of this ulcerogenic and carcinogenic bacterium.

Construction and optimization of pH-sensitive nanoparticle delivery system containing PLGA and UCCs-2 for targeted treatment of Helicobacter pylori

The acidic environment of the stomach is a threat to the curative effect of antimicrobial drugs for the eradication of Helicobacter pylori (H. pylori) in the infected area. The conventional clinical formulations of antibiotics have low specificity to H. pylori, which disrupts the normal balance of intestinal microbiomes. Therefore, oral drug delivery system with better stability at low pH as well as higher specificity to target H. pylori would provide more effective strategy to eradicate H. pylori and reduce the side effect of antibiotics. Based on the construction of UreI-mediated targeted drug delivery system developed by our group, in this work, using urea-modified UCCs-2 as targeting moiety to the UreI channel protein which is specifically expressed on H. pylori, pH-sensitive amoxicillin-loaded AMX-PLGA/UCCs-2 nanoparticles produced by UCCs-2 and PLGA for targeted treatment of H. pylori infection were established. The nanoparticles were prepared by double emulsion-solvent evaporation method. To achieve a promising drug delivery system with favorable pH-sensitive properties, we adopted an orthogonal design to obtain the optimal formulation. The results showed that the optimized AMX-PLGA/UCCs-2 nanoparticles were in a favorable pH sensitive manner and exhibited low cytotoxicity, higher specificity and better anti-H. pylori efficiency than amoxicillin and non-targeting AMX-PLGA/Cs nanoparticle both in vitro and in vivo, which can protect the antimicrobial drugs against acidic environment and deliver them to targeted eradicate H. pylori in the infected location. The cellular uptake mechanism showed that AMX-PLGA/UCCs-2 nanoparticles are an effective UreI-mediated targeted drug delivery system for anti-H. pylori treatment, which can also be used as promising nanocarriers for oral delivery of other therapeutic drugs to targeted treat H. pylori.

Delivery of Helicobacter pylori HpaA to gastrointestinal mucosal immune sites using Lactococcus lactis and its immune efficacy in mice

OBJECTIVE

To develop a safe and effective oral vaccine against Helicobacter pylori using its HpaA protein expressed in Lactococcus lactis.

RESULTS

The gene encoding HpaA was obtained by PCR and ligated to pNZ8110-lysM following digestion with NaeI + SphI. The recombinant plasmid was transferred into E. coli for multiplication, and then into L. lactis. The recombinant L. lactis was induced to express HpaA, resulting in two products of 29 and 25 kDa, both of which yielded positive immunoreaction with mouse antisera against H. pylori, as confirmed by immunoblot assays. The 29 kDa product constituted 12% of the cell lysates. Oral inoculation with the engineered L. lactis evoked significantly elevated serum IgG level in mice (P < 0.05).

CONCLUSIONS

A novel engineered L. lactis strain was developed that efficiently produces whole HpaA protein with desired antigenicity and potent immunogenicity. It provides a basis for approaches to L. lactis-delivered anti-H. pylori vaccination.